Typical electromagnetic machines function by exposing electrically conductive windings in a stator to a magnetic field produced by magnets mounted on a turning rotor. The size of the air gap between the stator and the rotor is an important design variable, as the electromagnetic efficiency of such machines tends to improve as the air gap size is reduced. Maintaining a constant air gap size is also important, both to avoid a collision between the rotor and the stator and to avoid unwanted currents, flux effects, and other load-related losses caused by eccentricities in the air gap. Consistency in air gap size is typically achieved by ensuring that the machine's stator and rotor (and any supporting structure) are stiff enough to withstand expected outside forces during assembly and operation. Significant violations of air gap size, such as where the air gap is nearly closed or is closed altogether, can be dangerous or destructive to equipment and personnel, particularly if the air gap is compromised during operation of the electromagnetic machine.
As the size of an electromagnetic machine increases, dependence on structural stiffness to ensure that a minimum air gap clearance is maintained can become impractical due to the weight and cost of the required structure. A need exists, therefore, for alternative approaches for maintaining a constant air gap. A need also exists for providing such alternatives that would provide the necessary gap clearance at a relatively lower weight and cost compared to known conventional methods that include increasing structural stiffness.